Formula
Net area is wall length times wall height, minus the openings.
Litres are the net area times the number of coats, divided by the coverage of one litre.
Among tins that hold the paint in a single can, the smallest is suggested. If that can would be left more than half full, the next smaller size is used instead, even if that means more than one can.
Worked example
8 m by 2.4 m minus 2.8 m² of openings is 16.400 m².
2 coats at 12 m² per litre need 2.73 litres. The suggested tin is 1 × 5 L.
Assumptions
12 m² per litre per coat is a common interior emulsion figure, not a promise. The tin wins.
UK sizes on this page are 2.5 L, 5 L and 10 L. Australian sizes are 1 L, 4 L and 10 L.
Ceilings and skirtings are not separate modes. A ceiling is a length times a width with openings at zero.
Checked
Checked 10 November 2026. Dulux Trade in the UK lists 2.5 L, 5 L and 10 L. Bunnings lists Dulux Wash&Wear in 1 L, 4 L and 10 L. The starting coverage of 12 m² per litre is still not a tin figure.